The objective of the proposed research is to develop ultra-high resolution, thin film low-temperature superconductivity (LTS) SQUID magnetometers (UHRSM) with integrated pickup-loops. The UHRSM will be optimized for imaging of the magnetic fields produced by action currents, injury and developmental currents, remanent magnetization, and magnetic susceptibility in isolated living tissue and small experimental animal preparations. During Phase I, the applicants innovation in SQUID design and fabrication already produced a reliable, simple to operate, inexpensive SQUID sensor with integrated pick-up coils, whose flux noise was comparable to the best commercially available SQUID sensors. The integration of the SQUID sensor into a cryogenic system resulted in a prototype instrument currently incorporated into an active research program at Vanderbilt University. Their present design allows a window-to-SQUID spacing of less than 20mm. The prototype proposed to be developed under the Phase II project will be an inexpensive, modular, customizable, bench-top LTS SQUID instrument for biological research with spatial resolution below 100mm and field sensitivities on the order of 1pT/(square root Hz). The proposed instrument will be capable of making measurements that are impossible with any other electric or magnetic instrument, and should lead to new insights into cellular biology and electro- and magnetophysiology. The existing expertise will be exploited further to develop and improve SQUID sensors for general and custom biomagnetic applications which require higher-sensitivity SQUID magnetometers and gradiometers but lower spatial resolution. PROPOSED COMMERCIAL APPLICATION: The cryogenic technology, the expertise in SQUID design, and they STTR grant would allow us to target SQUID microscopes with spatial resolutions below 100 microm with sensitivities around 1 pT/Hz-1/2. The LTS SQUIDs enables new measurements with a higher bandwidth, a higher spatial resolution and a much faster scanning rate due to a superior signal to noise ratio. The market for such an instrument is not enormous, but we are convinced to sell 5-10 systems mainly used in research per year. However, should the instrument be widely accepted, for example, as quality control instrument in the immunodiagnostic industry or as instrument to perform NDE on electronic components, we could sell tens of systems per year.